1. Field of the Invention
The present invention relates generally to projection apparatuses, projection systems, and projection method.
2. Description of the Related Art
There are known techniques for pointing a surface, onto which an image is projected by a projector, with a pointing device and feeding back a text character, a line, a graphic object, or the like drawn with the pointing device onto the projection surface. For example, a technique disclosed in Japanese Patent Application Laid-open No. 2007-48135 employs the following method. When a graphic object is drawn on a projection surface using a pointing device, position information about the graphic object is specified by acquiring brightness or the like of coordinates of each of one-by-one pixel areas, for example. Image data of the newly created drawing is generated and projected onto a region indicated by the position information. When, for instance, a line is written using a pointing device, position information about each of pixels constituting the line is acquired, and image data corresponding to each position is projected.
In the conventional technique, it is necessary that a pattern for position detection, other image, and/or the like is properly projected onto the projection surface to acquire position information about a drawing-designated portion. However, in a situation where, for instance, a plurality of users write to the projection surface, a user can produce a shadow where a projection pattern is not projected onto the projection surface properly. As a result, a problem is likely occur that position information for drawing cannot be acquired.
Therefore, it is desirable to provide a projection apparatus that allows drawing to be performed even in a situation where a shadow cast onto a projection surface creates a portion where appropriate position detection is inhibited.